Merck Manual

Please confirm that you are a health care professional

honeypot link

Hyperemesis Gravidarum


Antonette T. Dulay

, MD, Main Line Health System

Reviewed/Revised Oct 2022

Hyperemesis gravidarum is severe nausea and vomiting during pregnancy that results in dehydration, weight loss, and ketosis. Diagnosis is clinical and by measurement of urine ketones, serum electrolytes, and renal function. Treatment is with temporary suspension of oral intake and with IV fluids, antiemetics if needed, and vitamin and electrolyte repletion.

Pregnancy frequently causes nausea and vomiting; the cause appears to be rapidly increasing levels of estrogens or the beta subunit of human chorionic gonadotropin (beta-hCG). Vomiting usually develops at about 5 weeks gestation, peaks at about 9 weeks, and disappears by about 16 or 18 weeks. It is often called morning sickness, but it can occur any time of day. Women with normal nausea and vomiting during pregnancy usually continue to gain weight and do not become dehydrated.

Hyperemesis gravidarum is an extreme form of normal nausea and vomiting during pregnancy. It can be distinguished because it causes the following:

  • Weight loss (> 5% of weight)

  • Dehydration

  • Ketosis

  • Electrolyte abnormalities (in many women)

As dehydration progresses, it can cause tachycardia and hypotension.

Diagnosis of Hyperemesis Gravidarum

  • Sometimes serial weight measurements

  • Urine ketones

  • Serum electrolytes and renal function tests

Clinicians suspect hyperemesis gravidarum based on symptoms (eg, onset, duration, and frequency of vomiting; exacerbating and relieving factors; type and amount of emesis). Serial weight measurements can support the diagnosis.

Differential diagnosis

Other disorders that can cause vomiting must be excluded; they include gastroenteritis Overview of Gastroenteritis Gastroenteritis is inflammation of the lining of the stomach and small and large intestines. Most cases are infectious, although gastroenteritis may occur after ingestion of drugs, medications... read more , hepatitis Overview of Acute Viral Hepatitis Acute viral hepatitis is diffuse liver inflammation caused by specific hepatotropic viruses that have diverse modes of transmission and epidemiologies. A nonspecific viral prodrome is followed... read more , appendicitis Appendicitis Appendicitis is acute inflammation of the vermiform appendix, typically resulting in abdominal pain, anorexia, and abdominal tenderness. Diagnosis is clinical, often supplemented by CT or ultrasonography... read more Appendicitis , cholecystitis Acute Cholecystitis Acute cholecystitis is inflammation of the gallbladder that develops over hours, usually because a gallstone obstructs the cystic duct. Symptoms include right upper quadrant pain and tenderness... read more , other biliary tract disorders, peptic ulcer disease Peptic Ulcer Disease A peptic ulcer is an erosion in a segment of the gastrointestinal mucosa, typically in the stomach (gastric ulcer) or the first few centimeters of the duodenum (duodenal ulcer), that penetrates... read more Peptic Ulcer Disease , intestinal obstruction Intestinal Obstruction Intestinal obstruction is significant mechanical impairment or complete arrest of the passage of contents through the intestine due to pathology that causes blockage of the bowel. Symptoms include... read more Intestinal Obstruction , hyperthyroidism Hyperthyroidism Hyperthyroidism is characterized by hypermetabolism and elevated serum levels of free thyroid hormones. Symptoms include palpitations, fatigue, weight loss, heat intolerance, anxiety, and tremor... read more Hyperthyroidism not caused by hyperemesis gravidarum (eg, caused by Graves disease), gestational trophoblastic disease Gestational Trophoblastic Disease Gestational trophoblastic disease is proliferation of trophoblastic tissue in pregnant or recently pregnant women. Manifestations may include excessive uterine enlargement, vomiting, vaginal... read more Gestational Trophoblastic Disease , nephrolithiasis, pyelonephritis Acute pyelonephritis Bacterial urinary tract infections (UTIs) can involve the urethra, prostate, bladder, or kidneys. Symptoms may be absent or include urinary frequency, urgency, dysuria, lower abdominal pain... read more , diabetic ketoacidosis Diabetic Ketoacidosis (DKA) Diabetic ketoacidosis (DKA) is an acute metabolic complication of diabetes characterized by hyperglycemia, hyperketonemia, and metabolic acidosis. Hyperglycemia causes an osmotic diuresis with... read more or gastroparesis, benign intracranial hypertension Idiopathic Intracranial Hypertension Idiopathic intracranial hypertension causes increased intracranial pressure without a mass lesion or hydrocephalus, probably by obstructing venous drainage; cerebrospinal fluid composition is... read more , and migraine headaches Migraine Migraine is an episodic primary headache disorder. Symptoms typically last 4 to 72 hours and may be severe. Pain is often unilateral, throbbing, worse with exertion, and accompanied by symptoms... read more .

Prominent symptoms in addition to nausea and vomiting often suggest another cause.

Tests for alternative diagnoses are done based on laboratory, clinical, or ultrasound findings.

Treatment of Hyperemesis Gravidarum

  • Temporary suspension of oral intake, followed by gradual resumption

  • Fluids, thiamin, multivitamins, and electrolytes as needed

  • Antiemetics if needed

  • Rarely, total parenteral nutrition

At first, patients are given nothing by mouth. Initial treatment is IV fluid resuscitation, beginning with 2 L of Ringer's lactate infused over 3 hours to maintain a urine output of > 100 mL/hour. If dextrose is given, thiamin 100 mg should be given IV first, to prevent Wernicke encephalopathy. This dose of thiamin should be given daily for 3 days.

Subsequent fluid requirements vary with patient response but may be as much as 1 L every 4 hours or so for up to 3 days.

Electrolyte deficiencies are treated; potassium, magnesium, and phosphorus are replaced as needed. Care must be taken not to correct low plasma sodium levels too quickly because too rapid correction can cause osmotic demyelination syndrome.

Vomiting that persists after initial fluid and electrolyte replacement is treated with antiemetics and other medications taken as needed:

  • Vitamin B6 10 to 25 mg orally every 8 hours or every 6 hours

  • Doxylamine 12.5 mg orally every 8 hours or every 6 hours (can be taken in addition to vitamin B6)

  • Promethazine 12.5 to 25 mg orally, IM, or rectally every 4 to 8 hours

  • Metoclopramide 5 to 10 mg IV or orally every 6 to 8 hours

  • Ondansetron 8 mg orally or IM every 12 hours (for use before 10 weeks gestation, potential risks of congenital defects should be considered)

  • Prochlorperazine 5 to 10 mg orally, IV, or IM every 6 hours OR 25 mg rectally 2 times a day, as needed

After dehydration and acute vomiting resolve, small amounts of oral fluids are given. Patients who cannot tolerate any oral fluids after IV rehydration and antiemetics may need to be hospitalized or given IV therapy at home and take nothing by mouth for a longer period (sometimes several days or more). Once patients tolerate fluids, they can eat small, bland meals, and diet is expanded as tolerated. IV vitamin therapy is required initially and until vitamins can be taken by mouth.

If treatment is ineffective, corticosteroids may be tried; eg, methylprednisolone 16 mg every 8 hours orally or IV may be given for 3 days, then tapered over 2 weeks to the lowest effective dose. Corticosteroids should be used for < 6 weeks and with extreme caution. They should not be used during fetal organogenesis (between 20 and 56 days after fertilization); use of these drugs during the 1st trimester is weakly associated with facial clefting. The mechanism for corticosteroids’ effect on nausea is unclear. In extreme cases, total parenteral nutrition (TPN) has been used, although its use is generally discouraged.

Rarely, progressive weight loss, jaundice, or persistent tachycardia may occur despite treatment. In such cases,termination of the pregnancy may be offered, if it is available.

Key Points

  • Hyperemesis gravidarum is severe nausea and vomiting during pregnancy that, unlike morning sickness, can cause weight loss, ketosis, dehydration, and sometimes electrolyte abnormalities.

  • Exclude other disorders that can cause vomiting based on the woman's symptoms.

  • Determine severity by measuring serum electrolytes, urine ketones, BUN, creatinine, and body weight.

  • Suspend oral intake at first, give fluids and nutrients IV, restore oral intake gradually, and give antiemetics as needed.

Drugs Mentioned In This Article

Drug Name Select Trade
Novarel, Ovidrel, Pregnyl
Aluvea , BP-50% Urea , BP-K50, Carmol, CEM-Urea, Cerovel, DermacinRx Urea, Epimide-50, Gord Urea, Gordons Urea, Hydro 35 , Hydro 40, Kerafoam, Kerafoam 42, Keralac, Keralac Nailstik, Keratol, Keratol Plus, Kerol, Kerol AD, Kerol ZX, Latrix, Mectalyte, Nutraplus, RE Urea 40, RE Urea 50 , Rea Lo, Remeven, RE-U40, RYNODERM , U40, U-Kera, Ultra Mide 25, Ultralytic-2, Umecta, Umecta Nail Film, URALISS, Uramaxin , Uramaxin GT, Urea, Ureacin-10, Ureacin-20, Urealac , Ureaphil, Uredeb, URE-K , Uremez-40, Ure-Na, Uresol, Utopic, Vanamide, Xurea, X-VIATE
Advocate Glucose SOS, BD Glucose, Dex4 Glucose, Glutol , Glutose 15 , Glutose 45 , Glutose 5
Aldex AN, Doxytex, Unisom
Anergan-50, Pentazine , Phenadoz , Phenergan, Phenergan Fortis, Prometh Plain, Promethegan
Gimoti, Metozolv, Reglan
Zofran, Zofran in Dextrose, Zofran ODT, Zofran Solution, Zuplenz
Compazine, Compazine Rectal, Compazine Solution, Compazine Syrup, Compro
A-Methapred, Depmedalone-40, Depmedalone-80 , Depo-Medrol, Medrol, Medrol Dosepak, Solu-Medrol
NOTE: This is the Professional Version. CONSUMERS: View Consumer Version
quiz link

Test your knowledge

Take a Quiz!